Shailesh- We migrated our NAV environment about one year ago with the help of our partner here are a few things that we did (did not do but would do again)
Do the users use the actual server name when they log onto NAV? If so i would implement a DNS record so next time you migrate to a new server you will not have to go to every user and tell them the new server name, you can just change the dns record and no one will be the wiser.
If you are using enhanced security change the security model to standard, this can be done in single user mode. We had issues with table locking due to syncing all the users on a remote session and our sql server kept locking tables because the way the enhanced security model handles permissions.
do not preform the migration the night before a holiday
Get help from your partner they will have done migrations many times and can advise further
Thanks for the reply, i just want to clear what the precaution i have to taken before hardware and sql server migration if you have any document regarding this can you share with me, because i don’t have partner this migration is done by me and my team, second thing i have read one pdf in which it has been mention that Navision 6.0 SP1 , is compatibility with SQL Server 2008 R2 and Windows 2008.